Half-Reaction — Definition, Formula, Properties & Uses | AllChemicals | AllChemicals

Also Known As	Electrode half-reaction, redox half-equation, oxidation half-reaction, reduction half-reaction

What is Half-Reaction?

A half-reaction is one of the two components of an oxidation-reduction (redox) reaction, representing either the oxidation half (loss of electrons) or the reduction half (gain of electrons). Half-reactions show explicitly the electrons transferred. They are used to balance redox equations systematically and to describe processes at individual electrodes in electrochemical cells.

Properties & Characteristics

Oxidation half-reaction: Red → Ox + ne⁻ (electrons produced). Reduction half-reaction: Ox + ne⁻ → Red (electrons consumed). Must be balanced for mass and charge. Combined: electrons cancel. Standard electrode potential (E°) assigned to each half-reaction. Oxidation potential = −(reduction potential).

Uses & Applications

Balancing redox equations (half-reaction method). Understanding electrode processes in electrolysis and galvanic cells. Calculating cell potentials (E°cell = E°cathode − E°anode). Corrosion analysis. Battery chemistry. Electrochemical synthesis. Biochemical redox processes (e.g., electron transport chain).

Safety Information

Conceptual tool — no direct safety concerns. Practical redox processes described by half-reactions may involve hazardous chemicals or high voltages.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Half-Reaction

Index All "H" terms

Synonyms Electrode half-reaction, redox half-equation, oxidation half-reaction, reduction half-reaction

Frequently Asked Questions

What is Half-Reaction?

A half-reaction is one of the two components of an oxidation-reduction (redox) reaction, representing either the oxidation half (loss of electrons) or the reduction half (gain of electrons). Half-reactions show explicitly the electrons transferred. They are used to balance redox equations systematically and to describe processes at individual electrodes in electrochemical cells.

What is Half-Reaction used for?

Is Half-Reaction hazardous?

More "H" Terms

Haber Process N₂ + 3H₂ ⇌ 2NH₃ | ΔH = −92 kJ/mol Hafnium Hf Half Cell Half Life Half-Cell E = E° − (RT/nF)lnQ Half-Life A(t) = A₀e^(−λt); t½ = ln2/λ Halide X⁻ (e.g., F⁻, Cl⁻, Br⁻, I⁻) Halogen F₂, Cl₂, Br₂, I₂, At; Group 17; ns²np⁵ valence configuration Halogenation C-X + Cl₂/Br₂ (hv or AlCl₃) → C-X(halogen); EAS or radical pathway Halogens Hard Acid Hard acid: small, highly charged, low polarisability (e.g., H⁺, Mg²⁺, Al³⁺) Hard Base Hard base: high EN, low polarisability (e.g., F⁻, OH⁻, NH₃, H₂O)

View all "H" terms →